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Re: No Cretaceous placental mammals?
On 6/22/07, Jeff Hecht <email@example.com> wrote:
Yes, I meant placentals (mea culpa, mea culpa).
Hehe. If I had a nickel for every time someone said "mammal" when they
meant "therian" or "placental"....
(Part of me wonders if monotremes should ever have been added ...
well, too late now.)
The Slack et al paper is well worth looking up. (Mol. Biol Evol 23 (6) 1144-1155, 2006). It's available at <http://mbe.oxfordjournals.org/cgi/reprint/msj124?ijkey=zaRIuJ8ctNRqLkV&k> and well worth looking at their rooted tree, which takes the divergence of neognathae and paleognathae back to 98 million years ago. The two key fossils that calibrate it are Vegavis at 66 million and Waimanu (a primitive penguin) at 62 million.
That is interesting. According to this there would have been over a
dozen lineages of avian making it through the extinction (and probably
quite a few more).